Plasma-enhanced atomic layer deposition of conductive material over dielectric layers

ABSTRACT

Methods of forming a conductive metal layer over a dielectric layer using plasma enhanced atomic layer deposition (PEALD) are provided, along with related compositions and structures. A plasma barrier layer is deposited over the dielectric layer by a non-plasma atomic layer deposition (ALD) process prior to depositing the conductive layer by PEALD. The plasma barrier layer reduces or prevents deleterious effects of the plasma reactant in the PEALD process on the dielectric layer and can enhance adhesion. The same metal reactant can be used in both the non-plasma ALD process and the PEALD process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/149,140, filed on Feb. 2, 2009, the entire content ofwhich is hereby incorporated by reference and should be considered partof this specification. This application is related to U.S. Pat. No.6,534,395, filed Mar. 6, 2001, issued Mar. 18, 2003; U.S. Pat. No.6,613,695, filed Aug. 31, 2001, issued Sep. 2, 2003; U.S. Pat. No.6,660,660, filed Aug. 31, 2001, issued Dec. 9, 2003; U.S. Pat. No.6,858,524, filed May 5, 2003, issued Feb. 22, 2005; and U.S. Pat. No.7,045,406, filed May 5, 2003, issued May 16, 2006. The entire contentsof all of the above applications are hereby incorporated by referenceand should be considered a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to methods and compositions for reducingthe detrimental effects of plasma on metal oxide dielectric layersduring plasma-enhanced atomic layer deposition (PEALD) of overlyingconductive materials.

2. Description of the Related Art

Plasma-enhanced atomic layer deposition (PEALD) is a gas phase chemicalprocess typically used to create extremely thin coatings. As intraditional atomic layer deposition (ALD) methods, in PEALD a reactionsurface is alternately and sequentially contacted with reactants suchthat a thin film is deposited. In PEALD, one reactant is a plasmareactant, such as hydrogen (H*) plasma or hydrogen-nitrogen plasma (forexample, NH*, NH₂*, NH₃*, or N*+H*). Frequently, a second reactant is anorganometallic or inorganic metal source chemical.

PEALD can be used to deposit a number of refractory metals andconductive metal alloys. These materials can be used, for example, asgate electrodes or capacitor electrodes in integrated circuits devices.Frequently, a conductive layer is deposited on a metal oxide dielectric.Problems can arise when the plasma used in the deposition process reactswith the metal-oxide dielectric in the first few deposition cycles andat least partially reduces the metal-oxide dielectric back to unoxidizedmetal or to a substoichiometric metal oxide state. This can result inpoor adhesion between the metal oxide dielectric and the overlyingconductive material. While this affects the common metal oxides used inintegrated circuit manufacturing, such as Ta₂O₅, TiO₂, HfO₂, ZrO₂,Al₂O₃, La₂O₃, this effect is particularly pronounced with Al₂O₃ andincreases as the plasma intensity (e.g., power, reaction time)increases.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, methods for formingintegrated circuit devices are provided. In some embodiments, themethods comprise depositing a plasma barrier layer directly over a metaloxide dielectric layer on a substrate by an atomic layer deposition(ALD) process. The ALD process comprises alternately and sequentiallycontacting the substrate with a metal reactant and a non-plasmareactant. A conductive layer is subsequently deposited directly over theplasma barrier layer by a plasma-enhanced atomic layer deposition(PEALD) process. The PEALD process comprises alternately andsequentially contacting the substrate with the metal reactant and aplasma reactant.

In another aspect, methods of forming a gate electrode are provided,comprising depositing a plasma barrier layer with a thickness of about 1to about 5 nm directly over a dielectric layer on a substrate in areaction space by a non-plasma ALD process and subsequently depositing aconductive material directly over the plasma barrier layer by aplasma-enhanced ALD process.

In another aspect, methods of forming an integrated circuit devicecomprising a TaCN layer over a metal oxide dielectric layer areprovided. In some embodiments, an amorphous TaCN layer is depositeddirectly over a metal oxide dielectric layer on a substrate by anon-plasma ALD process. A TaNC layer is deposited directly on theamorphous layer by a PEALD process.

In another aspect, an integrated circuit device is provided. Theintegrated circuit device comprises a dielectric layer, a plasma barrierlayer over the dielectric layer, and a conductive layer. In someembodiments, the plasma barrier may comprise a first metal and may bebetween about 0.25 nm and about 1.75 nm thick. The conductive layer maycomprise a second metal that is different from the first metal of theplasma barrier. However, in some embodiments, the first metal and secondmetal are the same. For example, the first and second metal may compriseTaCN.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from the Detailed Description ofthe Preferred Embodiments and from the appended drawings, which aremeant to illustrate and not to limit the invention, and wherein:

FIG. 1 is a block diagram of a process of forming a conductive layerover a dielectric material according to some embodiments.

FIGS. 2A-C are schematic illustrations of a method of forming aconductive layer over a dielectric material according to someembodiments.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

Methods for depositing conductive films or refractory metals over adielectric material, such as a metal oxide, by plasma-enhanced atomiclayer deposition (PEALD) are provided along with related compositionsand structures. When plasma is used in a PEALD process to deposit aconductive material over a dielectric, the plasma reactant can have adeleterious effect on the dielectric layer in at least the first fewcycles of the PEALD process. For example, when plasma, such as H* orNH*, NH₂*, NH₃*, or N*+H* plasma, reacts with a metal oxide, a thinlayer of the metal oxide may be reduced to unoxidized metal or asubstoichiometric metal oxide state. In a PEALD process in which aconductive material, such as metal, is deposited directly over metaloxide, this may result in poor adhesion between the metal and theunderlying metal oxide layer, making PEALD a less desirable method foruse in this context. However, by depositing a plasma barrier (orinterface layer) between the metal and metal oxide, as described herein,the detrimental effects of plasma on the dielectric layer can be reducedor eliminated with little to no effect on the device characteristics. Insome embodiments the plasma barrier layer is an amorphous metalinterface layer. The metal reactant that is used to deposit the plasmabarrier layer can be the same reactant that is used in the subsequentPEALD process for depositing an overlying conductive layer, thusimproving the efficiency of the process.

According to some embodiments of the invention, a plasma barrier, suchas a TaCN or TiN film is formed over a metal oxide dielectric layer,such as an Al₂O₃ dielectric layer, on a substrate by a non-plasma ALDprocess. Preferably, each ALD cycle comprises two distinct depositionsteps or phases. In a first phase of the deposition cycle (“the metalphase”), a first reactant comprising a metal such as tantalum is pulsedto the reaction space and chemisorbs onto the substrate surface, formingno more than about one monolayer on the surface of the substrate. Themetal source material in this phase is selected such that, under thepreferred conditions, the amount of source material that can be bound tothe surface is determined by the number of available binding sites andby the physical size of the chemisorbed species (including ligands). Thechemisorbed layer left by a pulse of the metal source chemical isself-terminated with a surface that is non-reactive with the remainingchemistry of that pulse. One of skill in the art will recognize that theself-limiting nature of this phase makes the entire ALD cycleself-limiting.

In some embodiments, the metal is tantalum and the metal source chemicalis TBTDET. In other embodiments the metal is titanium and the metalsource chemical is TiCl₄.

Excess metal source material and reaction byproducts (if any) areremoved from the reaction space, e.g., by purging with an inert gas.Excess metal source material and any reaction byproducts may be removedwith the aid of a vacuum generated by a pumping system.

In a second phase of the deposition cycle a second reactant, alsoreferred to herein as a “second source chemical”, is pulsed into thereaction space to react with the metal-containing molecules left on thesubstrate surface by the preceding pulse. In some embodiments the secondsource chemical is a nitrogen source compound, preferably NH₃, andnitrogen is incorporated into the film by the interaction of the secondsource chemical with the monolayer left by the metal source material. Inpreferred embodiments, reaction between the second source chemical andthe chemisorbed metal species produces a metal nitride film over thesubstrate.

Any excess second source chemical and reaction byproducts, if any, areremoved from the reaction space by a purging gas pulse and/or vacuumgenerated by a pumping system. Purge gas may be any inert gas, such as,without limitation, argon (Ar) or helium (He).

The first and second phases are repeated to form a plasma barrier of adesired thickness over the dielectric layer. The plasma barrier layermay comprise, for example, amorphous TaCN, as in the case where themetal reactant is TBTDET, or TiN, where the metal reactant is TiCl₄. Insome embodiments the plasma barrier layer is about 2-5 nm thick.

A conductive layer is subsequently deposited by a PEALD process over theplasma barrier. In the first phase of the PEALD process, the substratecomprising the plasma barrier is exposed to the same metal sourcechemical that was used in the ALD process for forming the plasmabarrier. For example, if TBTDET was used to form an amorphous TaCNbarrier layer, the substrate is exposed to TBTDET. Similarly, if TiCl₄was used to form a plasma barrier layer, TiCl₄ is used. Excess metalsource material and reaction byproducts (if any) are removed from thereaction space, e.g., by purging with an inert gas and/or with the aidof a vacuum pump.

In a second phase of the PEALD deposition cycle a plasma reactant isprovided to the reaction space to react with the metal-containingmolecules left on the substrate surface by the preceding pulse. Asmentioned above, in some embodiments the plasma is generated remotelyand pulsed to the reaction space. In other embodiments a reactant isprovided to the reaction space and the plasma is formed in situ. Thereaction between the second source chemical and the chemisorbed metalspecies produces a conductive film over the substrate. The first andsecond phases are repeated to produce a film of the desired thickness.In some embodiments, such as when the metal reactant is TBTDET, theplasma reactant may be hydrogen plasma. In other embodiments, such aswhen the metal reactant is TiCl4, the plasma reactant may be an NH*,NH₂*, NH₃*, or N*+H* plasma.

The plasma barrier protects the underlying dielectric from the effectsof the PEALD process, such that the qualities of the dielectric layerare not significantly changed during the PEALD process.

FIG. 1 illustrates an exemplary process flow. A dielectric layer isformed by depositing a dielectric material over a substrate 110. Thedielectric material is a metal oxide in some embodiments. For example,in some embodiments, the dielectric material may comprise one or more ofTa₂O₅, TiO₂, HfO₂, ZrO₂, Al₂O₃, La₂O₃, HfSiO_(x), HfZrO_(x), HfAlO_(x),and LnAlO_(x). Other known dielectric materials may also be used and canbe selected by the skilled artisan based on the particularcircumstances. In some particular embodiments the dielectric layer is anAl₂O₃ layer. The dielectric layer may be formed by any depositionprocess, such as by ALD or by chemical vapor deposition (CVD). In someembodiments a substrate is provided on which a dielectric layer has beenformed and step 110 may be omitted.

Next, a plasma barrier layer is deposited directly over the dielectricmaterial 120 Like the dielectric layer, the plasma barrier layer mayalso be deposited by any process. However, the deposition processtypically will not negatively impact the properties of the dielectriclayer. In some embodiments, the plasma barrier layer is deposited by anon-plasma atomic layer deposition (ALD) process 120. A non-plasma ALDprocess is one that does not use a plasma reactant.

Subsequently, a conductive material (or refractory metal) is depositeddirectly over the plasma barrier by a PEALD process 130. In this way,the potentially detrimental effect of the plasma during at least thefirst several PEALD cycles is reduced or avoided and good adhesion maybe maintained between the conductive material and the underlyingdielectric material.

The substrate is typically a work piece on which deposition is desiredand can comprise a variety of materials and structures. For example andwithout limitation, the substrate may comprise silicon, silica, coatedsilicon, metal, such as copper or aluminum, dielectric materials,nitrides, oxides and/or combinations of materials.

The reaction space is typically a volume in a reactor in whichconditions can be adjusted to effect film growth by ALD processes. Inpreferred embodiments deposition of the plasma barrier layer and theoverlying conductive material takes place in the same reaction space.The reaction space can include surfaces subject to all reaction gaspulses from which gases or particles can flow to the substrate, byentrained flow or diffusion, during normal operation. The reaction spacecan be, for example, the reaction chamber in a single-wafer ALD reactoror the reaction chamber of a batch ALD reactor, where deposition onmultiple substrates takes place at the same time. In addition, chemicalvapor deposition reactors can be adapted for use in the methods. Thereactor can be configured for plasma generation, either in situ orremote. Exemplary reactors include the EmerALD™ and Pulsar™ reactorsavailable from ASM America (Phoenix, Ariz.).

In certain embodiments, the substrate may already comprise a dielectricmaterial prior to being introduced to the reaction space. The dielectricmaterial may be deposited by any standard deposition process including,but not limited to, physical vapor deposition (PVD, i.e., sputtering),chemical vapor deposition (CVD), and ALD. In some embodiments thedielectric material is deposited onto the substrate in the same reactionspace as subsequent deposition of the plasma barrier layer and/or theconductive material. In other embodiments the dielectric material isdeposited in a different reaction space.

As discussed above, a non-plasma ALD process is used to deposit theplasma barrier layer over the dielectric material in the reaction space.ALD is a self-limiting process, whereby sequential and alternatingpulses of reactants are used to deposit no more than one atomic (ormolecular) monolayer of material per deposition cycle. The depositionconditions and precursors are selected to ensure self-saturatingreactions, such that an adsorbed layer in one pulse leaves a surfacetermination that is non-reactive with the gas phase reactants of thesame pulse. A subsequent pulse of a different reactant reacts with theprevious termination to enable continued deposition. Thus, each cycle ofalternated pulses leaves no more than about one monolayer of the desiredmaterial. Due to the size of the chemisorbed species and the number ofreactive sites, somewhat less than a monolayer may be deposited in eachcycle. The principles of ALD type processes have been presented, forexample, by T. Suntola in, e.g. the Handbook of Crystal Growth 3, ThinFilms and Epitaxy, Part B: Growth Mechanisms and Dynamics, Chapter 14,Atomic Layer Epitaxy, pp. 601-663, Elsevier Science B.V. 1994, thedisclosure of which is incorporated herein by reference.

In a typical ALD-type process for depositing a plasma barrier layer, onedeposition cycle comprises exposing the substrate to a first reactant,removing any unreacted first reactant and reaction byproducts from thereaction space, exposing the substrate to a second reactant, followed bya second removal step. The first reactant is preferably a metalprecursor and the second reactant is preferably a non-plasma reactantthat reacts with the metal reactant to form the desired film. A personskilled in the art would recognize that the ALD-type process may beginwith provision of either reactant. Depending on the particular materialbeing deposited, additional non-plasma reactants may be providedalternately and sequentially in the ALD process to provide a material ofthe desired composition.

The separation of reactants by inert gases, such as Ar, preventsgas-phase reactions between reactants and enables self-saturatingsurface reactions. Because the reactions self-saturate, stricttemperature control of the substrates and precise dosage control of theprecursors is not required. However, the substrate temperature ispreferably such that an incident gas species does not condense intomonolayers nor decompose on the surface. Surplus chemicals and reactionbyproducts, if any, are removed from the reaction space before the nextreactive chemical pulse is introduced into the chamber. Undesiredgaseous molecules can be effectively expelled from the reaction spacewith the help of an inert purging gas. The purging gas directs thesuperfluous molecules out of the chamber. A vacuum pump may be used toassist in the purging.

The material of the plasma barrier and thickness are selected such thatthe PEALD process for depositing the overlying conductive material doesnot significantly change the characteristics of the underlyingdielectric layer.

The plasma barrier layer typically comprises a metal and may be, forexample, an elemental metal, a conductive metal nitride, a metalcarbide-nitride, a metal carbide, a metal silicon nitride, or a metalsilicon carbide. The ALD process for depositing the plasma barrier layerpreferably uses the same metal precursor as the subsequent PEALD processfor depositing the overlying conductive layer. Thus, in someembodiments, the plasma barrier and the overlying conductive layercomprise the same metal. The plasma barrier may comprise, for example,one or more metals selected from the group consisting of titanium (Ti),zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta),chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), rhenium(Re), iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum(Pt), rhodium (Rh), iridium (Ir), ruthenium (Ru) and osmium (Os). Askilled artisan would realize that other materials may be used withinthe scope of the present invention.

Metal precursors that can be used in the ALD and PEALD processes areknown in the art and include both organic and inorganic metal compounds.In some embodiments, metal halide reactants, such as, e.g., TaCl₅ andHfCl₄, are used as metal precursors in the ALD deposition of the plasmabarrier (and/or in the deposition of the overlying conductive layer).These precursors are generally inexpensive and relatively stable, but atthe same time reactive towards different types of surface groups. Inother embodiments, the metal precursor is a vapor phase speciescomprising at least one of Ti, Hf, Zr, Si, Al, Ta, Sr, Ba, Sc, Y, La,Eu, and Dy.

In some particular embodiments, the metal reactant is a titaniumreactant. The titanium reactant may be, for example, TiCl₄. In otherparticular embodiments the metal reactant is a tantalum reactant. Insome embodiments the tantalum reactant is a tantalum halide. In otherembodiments the tantalum reactant istert-butylimido-tris(diethylamido)tantalum (TBTDET).

In some embodiments, the plasma barrier is a conductive metal nitrideand a non-plasma reactant comprises a nitrogen source that reacts withadsorbed metal reactant to form a metal nitride. In other embodiments,the plasma barrier is a conductive metal carbide and the non-plasmareactant comprises a carbon source that reacts with the adsorbed metalreactant to form a metal carbide. In other embodiments, the plasmabarrier is a conductive metal nitride-carbide and a carbon source isalso utilized. The carbon source and the nitrogen source may be the samecompound or may be different compounds.

The nitrogen source compound may be, for example, one or more of ammonia(NH₃) and its salts, hydrogen azide (HN₃) and the alkyl derivatesthereof, hydrazine (N₂H₄) and salts of hydrazine, alkyl derivates ofhydrazine, primary, secondary and tertiary amines, tertbutylamide,CH₃N₃, hydrazine hydrochloride, dimethyl hydrazine, hydroxylaminehydrochloride, methylamine, diethylamine, and triethylamine. A skilledartisan would realize that other materials may be used within the scopeof the present invention.

In other embodiments, a non-plasma reactant is a reducing agent thatreduces the metal reactant to an elemental metal.

Briefly, in a typical non-plasma ALD process a metal reactant isprovided into the reaction chamber. After sufficient time for the metalreactant to adsorb on the substrate surface, the excess metal reactantand reaction by-products, if any, are removed from the reaction space.This may be accomplished, for example, by purging and/or by evacuatingthe reaction space with the aid of a vacuum pump. In embodiments wherethe precursor is provided with the aid of an inert carrier gas, the samegas may be used to purge the reaction space by stopping the flow of theprecursor into the stream of the carrier gas, while continuing to flowthe carrier gas. A second, non-plasma reactant is then introduced intothe reaction space and removed in like manner after sufficient time forthe non-plasma reactant to react with the previously adsorbed metalreactant. Additional non-plasma reactants can be provided in the ALDprocess to achieve the desired composition.

FIG. 2A illustrates a substrate 210 with an overlying dielectric layer200. As illustrate in FIG. 2B, a plasma barrier 220 is deposited by anon-plasma ALD process directly over the dielectric layer 200.

A skilled artisan would understand that the plasma barrier is depositedto a thickness that prevents the plasma from reacting to a significantextent with the underlying dielectric layer. The plasma barrier maygenerally be about 0.1 nm to about 50 nm. For some embodiments, theplasma barrier may be about 0.5 nm to about 5 nm. In other embodiments,the plasma barrier may be about 0.5 nm to about 3.5 nm.

In some embodiments, the ALD cycle for depositing the plasma barriermaterial is repeated more than 120 times, preferably at least 200 timesto form a plasma barrier prior to PEALD of the conductive material.

Following deposition of the plasma barrier layer, a PEALD process isused to deposit a conductive material or refractory metal directly overthe plasma barrier. In some embodiments, the same metal reactant that isused in the deposition of the plasma barrier is used in the depositionof the overlying conductive material. The same metal reactant that wasused in the non-plasma ALD cycle may be used in the PEALD cycle. Inother embodiments, different metal reactants are used.

In some embodiments, in the first few PEALD cycles, the plasma reactantmay react with the plasma barrier. In some embodiments, the plasmareactant reacts with the plasma barrier in about the first about 10 to100 PEALD cycles.

In some embodiments, the plasma reactant changes the properties of atleast a portion of the plasma barrier, for example through one or moreof stoichiometric change, crystallization, increased density andlowering resistivity. For example, if the plasma barrier is formed of anamorphous metal, during PEALD, a portion of the amorphous metal may beconverted into a crystalline metal phase. In some embodiments, theproperties of about 1 to 5 nm, more preferably about 3 to 4 nm of theplasma barrier are changed. The remaining portion of the plasma barrieris preferably thin enough that it does not set the work function oradversely impact the device characteristics. In some embodiments, onlyabout 1 to 5 nm, more preferably about 1 to 2 nm of the plasma barrierremains unchanged following PEALD deposition of the overlying conductivematerial. In some embodiments, between about 0.25 nm and about 1.75 nmof the plasma barrier remains unchanged following PEALD deposition ofthe overlying conductive material. In still other embodiments, betweenabout 0.125 nm and about 0.875 nm or between about 0.05 nm and about0.35 nm of the plasma barrier remains unchanged.

In certain embodiments, the plasma barrier comprises an amorphousmaterial, a portion of which is converted to a crystalline form duringPEALD of the overlying conductive material. The converted crystallinematerial from the plasma barrier may be the same in material andstructure as and may substantially align with the PEALD depositedconductive material. A skilled artisan would therefore consider theconverted portion of the plasma barrier in determining the desiredthickness of the conductive material. For example, the plasma barriermay be deposited as an amorphous metal nitride. Following PEALD of anoverlying conductive metal nitride, a portion of the amorphous metalnitride of the barrier layer is converted to the same crystalline metalnitride as the overlying conductive layer.

The overlying conductive material may be any conductive material knownin the art, including conductive metal alloys. For example, theconductive material may be TaCN or TiN. In other embodiments theconductive material is a refractory metal.

Generally, a metal precursor and one or more plasma reactants areintroduced into the reaction chamber alternately and sequentially. Themetal reactant can be generally as described above with respect to theplasma barrier. In some embodiments, the plasma reactant may be aplasma-excited species of hydrogen or a hydrogen-nitrogen plasmagenerated by, e.g., an in situ or remote plasma generator. Additionalreactants may be utilized to achieve the desired composition, as will berecognized by the skilled artisan.

Plasma-excited species of hydrogen may include, without limitation,hydrogen radicals (H*) and hydrogen cations (e.g., H⁺, H₂ ⁺), plasma, orother plasma-excited species known to a person skilled in the art.Plasma-excited species of hydrogen may be formed in situ or remotely,for example from molecular hydrogen (H₂) or hydrogen-containingcompounds (e.g., silane, diborane, etc). In other embodiments the plasmareactant is a hydrogen-nitrogen plasma (for example, NH*, NH₂*, NH₃*, orN*+H*) or a hydrogen-carbon plasma (CH*). In some embodiments, more thanone plasma reactant is used to produce a conductive material with thedesired composition.

Briefly, a metal reactant is provided into the reaction chamber. In someembodiments, the metal reactant is the same reactant that was used todeposit the plasma barrier layer. After sufficient time for the metalprecursor to adsorb on the substrate surface, the excess metal reactantand reaction by-products, if any, are removed from the reaction space.This may be accomplished, for example, by purging and/or by evacuatingthe reaction space with the aid of a vacuum pump. In embodiments wherethe precursor is provided with the aid of an inert carrier gas, the samegas may be used to purge the reaction space by stopping the flow of theprecursor into the stream of the carrier gas, while continuing to flowthe carrier gas. The second precursor is then introduced into thereaction space and removed in like manner after sufficient time for thesecond precursor to adsorb onto the substrate surface. As noted above,typically, the plasma reactant in the first about 10 to about 100 PEALDcycles may react with the plasma barrier 220. As the thickness of theconductive layer 230 increases during deposition, less plasma reactswith the plasma barrier 220.

FIG. 2C shows the structure of FIG. 2B after deposition of an overlyingconductive layer according to some embodiments. The structure comprisesa dielectric material 200, such as a metal oxide, over the substrate210. The plasma barrier 220 is formed on the dielectric material 200.The PEALD process forms a conductive material 230, for example acrystalline conductive metal nitride, over the dielectric material 200.When the plasma reactant from the PEALD process reacts with the plasmabarrier 220, at least a portion 240 of the plasma barrier 220 isconverted to a different phase, while a portion remains in theunconverted phase 250. In certain embodiments, the unconverted phase 250is an amorphous material, such as a metal, and the converted phase 240is the same material, but in a crystalline phase. In some embodiments,the converted metal phase 240 is the same as the overlying conductivematerial 230. In still other embodiments, the converted crystallinematerial 240 and the conductive material 230 substantially align intheir crystalline structure to form a consolidated conductive layer 260.

In some embodiments, the converted plasma barrier 240 is between about 1nm and about 5 nm, more preferably between about 3 nm and about 4 nm. Insome embodiments, the unconverted plasma barrier 250 is between about 1nm and about 5 nm, more preferably between about 1 nm and about 2 nm. Inother embodiments, the unconverted plasma barrier 250 is between about0.25 nm and about 1.75 nm. In still other embodiments, the unconvertedplasma barrier 250 is between about 0.125 nm and about 0.875 nm orbetween about 0.05 nm and about 0.35 nm.

Example 1

A TiN plasma barrier layer was deposited as a plasma barrier layer on anAl₂O₃ dielectric layer prior to deposition of a TiN conductive layer byPEALD.

Plasma Barrier

A titanium nitride (TiN) barrier layer was deposited on an aluminumoxide (Al₂O₃) dielectric material on a substrate by an ALD-type process.The sequence of steps in the process included alternately andsequentially pulsing a metal compound (TiCl₄), a nitrogen sourcecompound (NH₃), and a purge gas (Ar) into a reaction space containingthe substrate at a reaction temperature of about 375° C. The sequence ofgas pulses and purges was as follows:

(1) TiCl₄ pulse;

(2) Ar purge;

(3) NH₃ pulse; and

(4) Ar purge.

Steps (1)-(4) were repeated to form a uniform TiN barrier layer of about5 nm.

Conductive Layer

A TiN conductive layer was then deposited directly on the TiN barrierlayer by a plasma-enhanced ALD-type process in the same reactionchamber. A metal compound (TiCl₄), a hydrogen-nitrogen (NH*) plasma, anda purge gas (Ar) were alternately and sequentially pulsed into areaction space containing the substrate at a reaction temperature ofabout 375° C. The sequence of gas pulses and purges was as follows:

(1) TiCl₄ pulse;

(2) Ar purge;

(3) NH* pulse; and

(4) Ar purge.

Steps (1)-(4) were repeated to form a uniform TiN conductive layer ofabout 10 nm. The NH* plasma converted up to 4 nm of the amorphous TiN tocrystalline TiN, leaving about 1-2 nm of amorphous TiN between the Al₂O₃dielectric material and the crystalline TiN conductive layer.

Example 2

A TaCN plasma barrier layer was deposited as a plasma barrier layer onan Al₂O₃ dielectric layer by thermal ALD prior to deposition of a TaCNconductive layer by PEALD.

Plasma Barrier

An amorphous TaCN layer was deposited as a plasma barrier layer on anamorphous aluminum oxide (Al₂O₃) dielectric material on a substrate byan ALD-type process. The sequence of steps in the process includedalternately and sequentially pulsing a tantalum compound (TBTDET), anitrogen source compound (NH₃), and a purge gas (Ar) into a reactionspace containing the substrate at a reaction temperature of about 300°C., reaction pressure of about 1.5 Ton, and power of about 275 W. Thesequence of gas pulses and purges was as follows:

(1) TBTDET pulse;

(2) Ar purge;

(3) NH₃ pulse; and

(4) Ar purge.

Steps (1)-(4) were repeated to form a uniform TaCN barrier layer ofabout

15 Å having a resistivity of about 30 mΩcm-2 Ωcm with a density of about9.5-10.5 g/cc.

Conductive Layer

A TaCN conductive layer was then deposited directly on the plasmabarrier layer by a plasma-enhanced ALD-type process in the same reactionchamber. TBTDET, a hydrogen (H*) plasma, and a purge gas (Ar) werealternately and sequentially provided into a reaction space containingthe substrate at a reaction temperature of about 375° C. The sequence ofgas pulses and purges was as follows:

(1) TBTDET pulse;

(2) Ar purge;

(3) H* pulse; and

(4) Ar purge.

Steps (1)-(4) were repeated to form a uniform TaCN conductive layer ofabout 10 nm having a controllable resistivity of about 240 μΩcm-2000μΩcm with a density of about 11-12.5 g/cc and a variable latticeconstant. The H* converted up to 4 nm of the amorphous TaCN tocrystalline TaCN, leaving about 1-2 nm of amorphous TaCN between theAl₂O₃ dielectric material and the crystalline TiN conductive layer.

Example 3

A TaCN plasma barrier layer was deposited as a plasma barrier layer onan Al₂O₃ dielectric layer by thermal ALD prior to deposition of a TaCconductive layer by PEALD.

Plasma Barrier

An amorphous TaCN layer was deposited as a plasma barrier layer on agamma phase aluminum oxide (Al₂O₃) dielectric material on a substrate byan ALD-type process. The sequence of steps in the process includedalternately and sequentially pulsing a tantalum compound (TBTDET), anitrogen source compound (NH₃), and a purge gas (Ar) into a reactionspace containing the substrate at a reaction temperature of about 300°C., reaction pressure of about 1.5 Ton, and power of about 275 W. Thesequence of gas pulses and purges was as follows:

(1) TBTDET pulse;

(2) Ar purge;

(3) NH₃ pulse; and

(4) Ar purge.

Steps (1)-(4) were repeated about 120 cycles to form a uniform TaCNbarrier layer having a resistivity of about 30 mΩcm-2 Ωcm with a densityof about 9.5-10.5 g/cc.

Conductive Layer

A TaC conductive layer was then deposited directly on the plasma barrierlayer by a plasma-enhanced ALD-type process in the same reactionchamber. TBTDET, a hydrogen (H*) plasma, and a purge gas (Ar) werealternately and sequentially provided into a reaction space containingthe substrate at a reaction temperature of about 375° C. The sequence ofgas pulses and purges was as follows:

(1) TBTDET pulse;

(2) Ar purge;

(3) H* pulse; and

(4) Ar purge.

Steps (1)-(4) were repeated to form a uniform TaC conductive layer ofabout 10 nm having a controllable resistivity of about 240 μΩcm-2000μΩcm with a density of about 11-12.5 g/cc and a variable latticeconstant. The H* converted up to 4 nm of the amorphous TaCN tocrystalline TaCN, leaving about 1-2 nm of amorphous TaCN between theAl₂O₃ dielectric material and the crystalline TaCN conductive layer.

As will be apparent to the skilled artisan, various modifications,omissions and additions may be made to the methods and structuresdescribed above without departing from the scope of the invention. Allsuch modifications and changes are intended to fall within the scope ofthe invention, as defined by the appended claims.

1. A method for forming an integrated circuit comprising: depositing aplasma barrier directly over a metal oxide dielectric layer on asubstrate by an atomic layer deposition (ALD) process, wherein the ALDprocess comprises alternately and sequentially contacting the substratewith a metal reactant and a non-plasma reactant; and depositing aconductive layer by a plasma-enhanced atomic layer deposition (PEALD)process directly over the plasma barrier, wherein the PEALD processcomprises alternately and sequentially contacting the substrate with themetal reactant and a plasma reactant.
 2. The method of claim 1, whereinthe metal oxide dielectric layer comprises Al₂O₃.
 3. The method of claim1, wherein the plasma barrier is deposited to a thickness of about 0.5nm to about 5 nm.
 4. The method of claim 1, wherein the plasma barriercomprises an amorphous metal nitride prior to deposition of theconductive layer.
 5. The method of claim 4, wherein a portion of theamorphous metal nitride plasma barrier is converted to a crystallinephase during the PEALD process.
 6. The method of claim 1, wherein themetal reactant comprises a metal selected from the group consisting ofTi, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, and Ni.
 7. The methodof claim 6, wherein the metal reactant comprises a metal halide.
 8. Themethod of claim 7, wherein the metal reactant comprises TiCl₄.
 9. Themethod of claim 6, wherein the metal reactant comprises organo-metallicprecursors.
 10. The method of claim 1, wherein the non-plasma reactantis selected from the group consisting of ammonia (NH₃) and its salts,hydrogen azide (HN₃) and the alkyl derivates thereof, hydrazine (N₂H₄)and salts of hydrazine, alkyl derivates of hydrazine, primary, secondaryand tertiary amines, tertbutylamide, CH₃N₃, hydrazine hydrochloridedimethyl hydrazine, hydroxylamine hydrochloride, methylamine,diethylamine, and triethylamine.
 11. The method of claim 1, wherein theplasma reactant is a hydrogen or hydrogen-nitrogen plasma.
 12. Themethod of claim 11, wherein the hydrogen-nitrogen plasma is selectedfrom the group consisting of NH*, NH₂*, NH₃*, and N*+H*.
 13. The methodof claim 1, wherein the plasma barrier comprises amorphous TaCN.
 14. Themethod of claim 13, wherein at least a portion of the amorphous TaCN isconverted to crystalline TaCN during the PEALD process.
 15. The methodof claim 1, wherein the plasma barrier comprises TiN.
 16. A method offorming a gate electrode comprising: depositing a plasma barrier layerwith a thickness of about 1 to 5 nm directly over a dielectric layer ona substrate in a reaction space by a non-plasma atomic layer deposition(ALD) process; and depositing a conductive material directly over theplasma barrier layer by a plasma-enhanced atomic layer deposition(PEALD) process.
 17. The method of claim 16, wherein the non-plasma ALDprocess comprises: contacting the substrate with a vapor phase pulse ofa first metal reactant; removing excess first metal reactant from thereaction space; contacting the substrate with a non-plasma secondreactant; and removing excess second reactant from the reaction space.18. The method of claim 17, wherein the PEALD process comprises:contacting the substrate with a third metal reactant; removing excessthird metal reactant from the reaction space; contacting the substratewith a fourth plasma reactant; and removing excess fourth reactant fromthe reaction space.
 19. The method of claim 18, wherein the first metalreactant and the third metal reactant are the same.
 20. The method ofclaim 18, wherein the plasma is generated in situ.
 21. The method ofclaim 18, wherein the plasma is generated remotely.
 22. The method ofclaim 16, wherein the non-plasma ALD process and the PEALD process arecarried out in the same reaction space.
 23. The method of claim 16,wherein the dielectric layer comprises a metal oxide.
 24. A method offorming an integrated circuit device comprising a TaCN layer over ametal oxide dielectric layer comprising: depositing an amorphous TaCNlayer directly over a metal oxide dielectric layer on a substrate by anon-plasma atomic layer deposition (ALD) process; and depositing a TaNClayer directly on the amorphous TaCN layer by a plasma-enhanced ALDprocess.
 25. The method of claim 24, wherein the same metal reactant isused in the non-plasma ALD process and the PEALD process.
 26. The methodof claim 25, wherein the metal reactant is TBTDET.
 27. The method ofclaim 24, wherein the non-plasma ALD process comprises alternately andsequentially contacting the substrate with TBTDET and NH₃.
 28. Themethod of claim 24, wherein the PEALD process comprises alternately andsequentially contacting the substrate with TBTDET and hydrogen plasma(H*).
 29. An integrated circuit device comprising: a dielectric layer; aplasma barrier over the dielectric layer comprising a first metal,wherein the plasma barrier is between about 0.25 nm and about 1.75 nmthick; and a conductive layer over the plasma barrier comprising asecond metal.
 30. The integrated circuit device of claim 29, whereinfirst and second metal are the same.
 31. The integrated circuit deviceof claim 29, wherein the plasma barrier is between about 0.125 nm andabout 0.875 nm thick.
 32. The integrated circuit device of claim 31,wherein the plasma barrier is between about 0.05 nm and about 0.35 nmthick.
 33. The integrated circuit device of claim 29, wherein the plasmabarrier is amorphous and the conductive layer is crystalline.
 34. Theintegrated circuit device of claim 29, wherein the first metal has afirst structure and the second metal has a second structure and whereinthe first structure and the second structure substantially align. 35.The integrated circuit device of claim 29, wherein the dielectric layeris chosen from the group consisting of Ta₂O₅, TiO₂, HfO₂, ZrO₂, Al₂O₃,La₂O₃, HfSiO_(x), HfZrO_(x), HfAlO_(x), and LnAlO_(x).
 36. Theintegrated circuit device of claim 35, wherein the dielectric layer isAl₂O₃.
 37. The integrated circuit device of claim 29, wherein the plasmabarrier comprises an elemental metal, a conductive metal nitride, ametal carbide-nitride, a metal carbide, a metal silicon nitride, or ametal silicon carbide.
 38. The integrated circuit device of claim 29,wherein the plasma barrier comprises at least one of the groupconsisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Pd,Pt, Rh, Ir, Ru and Os.
 39. The integrated circuit device of claim 38,wherein the plasma barrier comprises TaCN.
 40. The integrated circuitdevice of claim 29, wherein the conductive layer is chosen from thegroup consisting of TaCN and TiN.
 41. The integrated circuit device ofclaim 40, wherein the conductive layer comprises TaCN.